Question: Simplify the following expression: $t = \dfrac{1}{6z} + \dfrac{1}{9z}$
Explanation: In order to add expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $6z$ and $9z$ $\lcm(6z, 9z) = 18z$ $ t = \dfrac{3}{3} \cdot \dfrac{1}{6z} + \dfrac{2}{2} \cdot \dfrac{1}{9z} $ $t = \dfrac{3}{18z} + \dfrac{2}{18z}$ $t = \dfrac{3 +2}{18z}$ $t = \dfrac{5}{18z}$